<p>A shift control system for a vehicle transmission (M) with multiple gear trains and connected to an engine crankshaft (CR) through a clutch (C) for shifting without disengaging the clutch (C). In conducting a shifting operation through a roller synchro mechanism (R) associated with a gear train, the number of revolutions of the engine crankshaft (CR) is promptly decreased through at least one of an ignition control means (M1) and a fuel supply control means (M2) to synchronize the number of revolutions of a main shaft (Sm) and a counter shaft (Sc) of the transmission when the number of revolutions of the main shaft (Sm) is greater than the number of revolutions for synchronizing with the counter shaft (Sc) and the number of revolutions of the engine crankshaft (CR) is increased to synchronize the number of revolutions of the main shaft (Sm) and the counter shaft (Sc) when the number of revolutions of the main shaft (Sm) is less than the number of revolutions for synchronizing with the counter shaft (Sc). This enables a prompt shifting. <IMAGE></p>
